An electric drive system is connected to a power battery pack to drive a motor, the motor includes an exciting winding, and the electric drive system includes a bus, a three-level inverter circuit, an electric excitation circuit, and a controller. The bus includes a positive bus and a negative bus. The three-level inverter circuit includes a first bus capacitor and a second bus capacitor. The first bus capacitor is connected between the positive bus and a bus midpoint, and the second bus capacitor is connected between the negative bus and the bus midpoint. A first input terminal of the electric excitation circuit is connected in parallel to the first bus capacitor, a second input terminal of the electric excitation circuit is connected in parallel to the second bus capacitor, and an output terminal of the electric excitation circuit is connected to the exciting winding of the motor.
Legal claims defining the scope of protection, as filed with the USPTO.
4. The electric drive system according to claim 3, wherein the controller is further configured to adjust switching frequencies of control signals of the first excitation circuit and the second excitation circuit to adjust output currents of the first excitation circuit and the second excitation circuit; a value of the output current of the first excitation circuit is positively correlated with the positive bus and an offset amplitude of the electric potential of the bus midpoint; and a value of the output current of the second excitation circuit is positively correlated with the negative bus and the offset amplitude of the electric potential of the bus midpoint.
6. The electric drive system according to claim 5, wherein the first rectifier circuit and the second rectifier circuit comprise controllable switching transistors, and the controller is further configured to control working states of the controllable switching transistors to adjust output currents of the first rectifier circuit and the second rectifier circuit.
8. The electric drive system according to claim 7, wherein the controller is further configured to control working states of the first LLC resonant conversion circuit and the second LLC resonant conversion circuit based on a same control signal.
9. The electric drive system according to claim 8, wherein the controller is further configured to adjust a switching frequency of the control signal based on an excitation current needed by the exciting winding.
10. The electric drive system according to claim 7, wherein the third rectifier circuit comprises controllable switching transistors, and the controller is further configured to control working states of the controllable switching transistors to adjust an output current of the third rectifier circuit.
11. The electric drive system according to claim 1, wherein the controller is further configured to control a working state of the three-level inverter circuit.
14. The electric excitation circuit according to claim 13, wherein an output terminal of the first excitation circuit is connected in parallel to an output terminal of the second excitation circuit, and then the two output terminals are connected to the output terminal of the electric excitation circuit.
20. The powertrain according to claim 19, wherein the controller is further configured to adjust switching frequencies of control signals of the first excitation circuit and the second excitation circuit to adjust output currents of the first excitation circuit and the second excitation circuit; a value of the output current of the first excitation circuit is positively correlated with the positive bus and an offset amplitude of the electric potential of the bus midpoint; and a value of the output current of the second excitation circuit is positively correlated with the negative bus and the offset amplitude of the electric potential of the bus midpoint.
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January 3, 2023
July 23, 2024
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